The observation of a picosecond transient in the relaxation of an iron porphyrin

Cornelius, P. A.; Steele, A W; Chernoff, Donald A.; Hochstrasser, R. M.

doi:10.1016/0009-2614(81)85096-8

Cited by 34 publications

(22 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The indirect pathway necessitates a spin conversion and, in turn, is slow (70 ps), whereas the direct pathway is spin‐allowed and faster (30 ps). For the tripheptet ( 7 T 1 ) excited state,29 sharp maxima at λ =490 and 630 nm emerge during our experiments. The kinetic control is augmented by very good overlaps between the porphyrin (π, π*) and the manganese (d, d*) orbitals and by interactions with several charge transfer states 27.…”

Section: Resultsmentioning

confidence: 62%

“…Characteristics of the latter state include maxima in the visible region at wavelengths of >490, 541, 595, and 634 nm that go together with ground state bleaching around λ =570 and 610 nm (Figure 7). 29 In the near‐infrared region, a maximum discernable around λ =800 nm directly after laser excitation resembles the general triplet markers of metalloporphyrins. Following its formation, the recombination of the triphexet ( 6 T 1 ) excited state competes with internal conversions to other tripmultiplets, including the tripoctet ( 8 T 1 ) excited state and ligand release (i.e., OH . )…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

Krokos

Spänig

Ruppert

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

A series of truly water-soluble C(60)/porphyrin electron donor-acceptor conjugates has been synthesized to serve as powerful mimics of photosynthetic reaction centers. To this end, the overall water-solubility of the conjugates was achieved by adding hydrophilic dendrimers of different generations to the porphyrin moiety. An important variable is the metal center of the porphyrin; we examined zinc(II), copper(II), cobalt(II), nickel(II), iron(III), and manganese(III). The first insights into electronic communication between the electron donors and the electron acceptors came from electrochemical assays, which clearly indicate that the redox processes centered either on C(60) or the porphyrins are mutually affected. Absorption measurements, however, revealed that the electronic communication in terms of, for example, charge-transfer features, remains spectroscopically invisible. The polar environment that water provides is likely to be a cause of the lack of detection. Despite this, transient absorption measurements confirm that intramolecular charge separation processes in the excited state lead to rapid deactivation of the excited states and, in turn, afford the formation of radical ion pair states in all of the investigated cases. Most importantly, the lifetimes of the radical ion pairs were found to depend strongly on several aspects. The nature of the coordinated metal center and the type of dendrimer have a profound impact on the lifetime. It has been revealed that the nature/electronic configuration of the metal centers is decisive in powering a charge recombination that either reinstates the ground state or any given multiplet excited state. Conversely, the equilibrium of two opposing forces in the dendrimers, that is, the interactions between their hydrophilic regions and the solvent and the electronic communication between their hydrophobic regions and the porphyrin and/or fullerene, is the key to tuning the lifetimes.

show abstract

Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

Krokos

Spänig

Ruppert

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Metalloporphyrin complexes are known as efficient photosensitizers in biological processes. Therefore, a wide number of different complexes, including MePC, were investigated (3)(4)(5)(6)(7)(8)(9)(10) with respect to their linear optical properties. These investigations have been focused on the study of the influence of different central metal ions on the ratio of radiative and nonradiative deactivation and on the ISC quantum yield.…”

Section: Introductionmentioning

confidence: 99%

On the Influence of Higher Excited States on the ISC Quantum Yield of Octa‐aL‐alkyloxy‐substituted Zn‐Phthalocyanine Molecules Studied by Nonlinear Absorption

RuUckmann¹,

Zeug

Herter

et al. 1997

Photochem & Photobiology

View full text Add to dashboard Cite

Abstract— Octa‐aL‐alkyloxy‐substituted Zn‐phthalocyanines are an interesting class of far red‐absorbing photosensitizers. The chemical structure, the calculated steric conformation, the observed linear optical properties and an anomalous luminescence from a higher than S, excited state are reported. To study the optical properties of higher excited states and their occupation dynamics up to delay times of 15 ns we have carried out measurements of transient absorption spectra after 14 ps pulsed, resonant B‐band and Q‐band excitation. From these measurements the excited state singlet‐singlet and triplet‐triplet spectra as well as the intersystem crossing (ISC) quantum yields are obtained. The main result is an excitation wavelength‐dependent ISC quantum yield that can be explained by an additional ISC channel between higher excited singlet and triplet states. The large rate of this channel is justified by the resonance between higher triplet states, observed in the triplet‐triplet spectrum and the B, absorption band. Using kinetic model calculations, a lifetime of the higher excited singlet state of some picoseconds is predicted and the influence of a two‐step absorption process on the population density of this higher excited singlet state is discussed.

show abstract

“…10a However, iron porphyrin may not be good triplet photosensitizers due to the short-lived triplet excited states. 14 ZnTPTBP absorbs in the red region, thus a 654 nm laser diode (12 mW, 95.5 mW cm À2 ) was used as the excitation source for TTA UC (Fig. 3).…”

mentioning

confidence: 99%

Zinc(ii) tetraphenyltetrabenzoporphyrin complex as triplet photosensitizer for triplet–triplet annihilation upconversion

et al. 2013

View full text Add to dashboard Cite

show abstract

The observation of a picosecond transient in the relaxation of an iron porphyrin

Cited by 34 publications

References 23 publications

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

On the Influence of Higher Excited States on the ISC Quantum Yield of Octa‐aL‐alkyloxy‐substituted Zn‐Phthalocyanine Molecules Studied by Nonlinear Absorption

Zinc(ii) tetraphenyltetrabenzoporphyrin complex as triplet photosensitizer for triplet–triplet annihilation upconversion

Contact Info

Product

Resources

About